73 lines
1.9 KiB
Go
73 lines
1.9 KiB
Go
|
package vm
|
||
|
|
|
||
|
|
import (
|
||
|
|
"fmt"
|
||
|
|
|
||
|
|
"github.com/CityOfZion/neo-go/pkg/vm/stack"
|
||
|
|
)
|
||
|
|
|
||
|
|
// VM represents an instance of a Neo Virtual Machine
|
||
|
|
type VM struct {
|
||
|
|
// ResultStack contains the results of
|
||
|
|
// the last evaluation stack before the program terminated
|
||
|
|
ResultStack stack.RandomAccess
|
||
|
|
// InvocationStack contains all of the contexts
|
||
|
|
// loaded into the vm
|
||
|
|
InvocationStack stack.Invocation
|
||
|
|
state Vmstate
|
||
|
|
}
|
||
|
|
|
||
|
|
// NewVM will:
|
||
|
|
// Set the state of the VM to NONE
|
||
|
|
// instantiate a script as a new context
|
||
|
|
// Push the Context to the Invocation stack
|
||
|
|
func NewVM(script []byte) *VM {
|
||
|
|
ctx := stack.NewContext(script)
|
||
|
|
v := &VM{
|
||
|
|
state: NONE,
|
||
|
|
}
|
||
|
|
v.InvocationStack.Push(ctx)
|
||
|
|
return v
|
||
|
|
}
|
||
|
|
|
||
|
|
// Run loops over the current context by continuously stepping.
|
||
|
|
// Run breaks; once step returns an error or any state that is not NONE
|
||
|
|
func (v *VM) Run() (Vmstate, error) {
|
||
|
|
for {
|
||
|
|
state, err := v.step()
|
||
|
|
if err != nil || state != NONE {
|
||
|
|
return state, err
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// step will read `one` opcode from the script in the current context
|
||
|
|
// Then excute that opcode
|
||
|
|
func (v *VM) step() (Vmstate, error) {
|
||
|
|
// Get Current Context
|
||
|
|
ctx, err := v.InvocationStack.CurrentContext()
|
||
|
|
if err != nil {
|
||
|
|
return FAULT, err
|
||
|
|
}
|
||
|
|
// Read Opcode from context
|
||
|
|
op, _ := ctx.Next() // The only error that can occur from this, is if the pointer goes over the pointer
|
||
|
|
// In the NEO-VM specs, this is ignored and we return the RET opcode
|
||
|
|
// Execute OpCode
|
||
|
|
state, err := v.executeOp(stack.Instruction(op), ctx)
|
||
|
|
if err != nil {
|
||
|
|
return FAULT, err
|
||
|
|
}
|
||
|
|
return state, nil
|
||
|
|
}
|
||
|
|
|
||
|
|
// ExecuteOp will execute one opcode on a given context.
|
||
|
|
// If the opcode is not registered, then an unknown opcode error will be returned
|
||
|
|
func (v *VM) executeOp(op stack.Instruction, ctx *stack.Context) (Vmstate, error) {
|
||
|
|
//Find function which handles that specific opcode
|
||
|
|
handleOp, ok := opFunc[op]
|
||
|
|
if !ok {
|
||
|
|
return FAULT, fmt.Errorf("unknown opcode entered %v", op)
|
||
|
|
}
|
||
|
|
return handleOp(op, ctx, &v.InvocationStack, &v.ResultStack)
|
||
|
|
}
|